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Repairing Critical-Sized Rat Calvarial Defects with Progenitor Cell-Seeded Acellular Periosteum: A Novel Biomimetic Scaffold
Scott J. Rapp, M.D.1, Donna C. Jones, Ph.D.2, Patrick Gerety, M.D.3, Jesse A. Taylor, M.D.4.
1University Hospital, Cincinnati, OH, USA, 2Cincinnati Children's Hospital Medical Center, Cincinnati, OH, USA, 3The University of Pennsylvania and Children’s Hospital of Philadelphia, Philadelphia, PA, USA, 4University of Pennsylvania and Children’s Hospital of Philadelphia, Philadelphia, PA, USA.
PURPOSE:
The importance of periosteum in the growth, maintenance, and overall health of bone has long been recognized. Like bone, the body’s periosteum is in limited supply, and its harvest is not without moribidity. There is increasing data from our lab and others supporting its role in bone tissue engineering. The purpose of this study is to engineer neo-periosteum by using a combination of acellular periosteum, growth factors, and mesenchymal stem cells to aid in bone allograft revitalization in a rat calvarial defect model.
METHODS:
Antigenic bovine periosteum was harvested and processed (RTI Biologics) and the cambial layer was then seeded with adipose-derived stromal cells (ASC) or periosteal-derived stromal cells (PSC) harvested from a highly-inbred Lewis rat and incubated for 14 days. In-vitro adherence for both cell types was verified through SEM and conventional histology. Bilateral, full-thickness, 5 mm diameter calvarial defects were created in 19 rats. These were filled with xenograft bone chips and covered with acellular periosteum treated with combinations of growth factors (VEGF, BMP-2, or both) and mesenchymal stem cells [adipose-derived (ASC’s) and periosteal-derived(PSC’s)]. Appropriate controls were also performed. Rats were sacrificed 56 days post-surgery. Bone deposition was quantified by micro-CT and viability was determined histologically. Significance was determined through ANOVA.
RESULTS:
The addition of stem cells to the acellular periosteum significantly increased de novo bone growth (p < 0.001), as did the addition of growth factors (p < 0.001), relative to controls. ASCs demonstrated a greater amount of calcified material within the defects over PSCs when evaluated by micro-CT, 17.01 mm³ vs. 15.32 mm³ respectively. Although the stem cell source did not influence revitalization histologically (p = 0.242), the combination of growth factors was statistically more effective (p > 0.001). In the ASC group, addition of VEGF/BMP-2 had the highest percentage of new bone growth (81%) when compared to no growth factor (65%). A significant interaction indicated that the two cell types did not respond equally to growth factors (p = 0.039).
CONCLUSION:
Acellular periosteum represents an effective scaffold for mesenchymal stem cell adherence. Engineering “neo-periosteum” for bone allograft revitalization is a novel strategy for bone tissue engineering.
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